Various devices have been proposed for obtaining desired radiographic alignments of X-ray sources relative to viewing screens or films. These have included electro-optical devices and various mechanical devices, to stabilize the geometry. However, none are automated via a feedback loop, or equivalent means, so as to determine appropriate geometry during the radiographic process. Therefore, there is a need to overcome this shortcoming, for example by the use of a multiple-source system which provides two-dimensional registration based on user selectable criteria and which can involve all aspects of the radiographic image, including data derived from previous examinations.
A preliminary search of the prior art reveals the following prior U.S. patents of interest, which appear to show the present state of the patented art:
Hartmann, U.S. Pat. No. 3,673,394 PA1 Gasaway, U.S. Pat. No. 3,714,428 PA1 Damman et al, U.S. Pat. No. 3,873,834 PA1 Ennslin et al, U.S. Pat. No. 3,906,227 PA1 Cowell et al, U.S. Pat. No. 3,932,756 PA1 Albert, U.S. Pat. No. 3,949,229 PA1 Zermano et al, U.S. Pat. No. 4,085,324
Also of interest, and pertinent to the subject matter of the present invention, are the following publications:
Fujimura et al, "Computer Controlled Radiography for Observation of Movements of Articulatory and Other Human Organs", Comput. Biol. Med., Pergamon Press (Great Britain), 1973, Vol. 3, pp. 371-384. PA0 McKee et al, "Computer Recognition of Partial Views of Curved Objects", IEEE Transactions on Computers, Vol. C-26, No. 8, August 1977, pp 790-800. PA0 Wong, "Sensor Transformations", IEEE Transactions on Systems, Man and Cybernetics, Vol. SMC-7, No. 12, December 1977, pp 836-841. PA0 Ulstad, "An Algorithm for Estimating Small Scale Differences Between Two Digital Images", Pattern Recognition, Pergamon Press (Great Britain), 1973, Vol. 5, pp 323-333. PA0 Perry et al, "Medical Image Reconstruction: Multiangular Sectional Roentgenography by Computer", NCAR Technical Note (National Center for Atmospheric Research, Boulder, Colo.), August 1975, NCAR-TN/STR-108.